Profiled bottom wall for extruded and wall ironed cans

ABSTRACT

A profiled bottom wall for drawn, extruded and/or wall ironed cans having improved resistance against buckling under the internal pressure of a packaged medium. The profiled bottom wall includes an annular chime projecting inwardly and upwardly from the body wall which terminates in an annular bead. The construction is such that a 50 percent increase in resistance to buckling is achieved as compared to conventional bottom walls.

United States Patent Gailus et al.

[451 Sept. 12, 1972 [54] PROFILED BOTTOM WALL FOR Lang ..220/66 1,963,795 6/1934 EXTRUDED AND WALL IRONED CANS 3,272,383 9/1966 Harvey ..220/66 [72] Inventors: Walter J. Gailus, Chicago; James R. ggeg Hoenig, Tinley Park, both of Ill. [73] Assignee: Continental Cm Com any, In Primary Examiner-Joseph R. Leclair New York, N.Y. Assistant Examiner-James R. Garrett Filed April 28 1970 Attorney-Diner, Brown, Ramik & Holt 21 Appl. No.2 32,526 7] AB TRACT A profiled bottom wall for drawn, extruded and/or 521 U.S.Cl .2201, 220/70 Wall ironed cans having improved resistance against 51 Int. Cl. ..B65d 7/42 buckling under the internal Pressure of a Packaged [58] Field of Search 70 72/267 348 medium. The profiled bottom wall includes an annular chime projecting inwardly and upwardly from the [56] References Cmd body wall which terminates in an annular head. The

construction is such that a 50 percent increase in re- UNITED STATES PATENTS sistance to buckling is achieved as compared to conti b0 1 2,142,743 111939 Calleson et al. ..220/66 x m mm W s 287,624 10/1883 Chaumont ..220/70 9 Claims, 2 Drawing Figures l I D i 5 i I l l -A. R6 L/ W J I 1 L\ j I R?) F [R2 \4 1 a \7 7 D2 2' m-oz mama so .1 z m I [III-Ii FIG. 1.

H INVENTDRS- uoALTER J. GAILUS I B QJHMES R. oama A RNEYS PROFILED BOTTOM WALL FOR EXTRUDED AND WALL IRONED CANS In the manufacture of drawn, extruded and/or wall ironed cans, it is necessary to keep the body wall and bottom wall of the can as thin as possible in order to produce a competitively priced can. Since cans are produced and sold by the billions, a very small saving in the cost of the material for one can will produce a large difference in price on a normal order of several hunble since a customer will usually assume that the contents of the can are spoiled when the buckled bottom is detected. Accordingly, it is highly desirable to provide a bottom whose profile has a high degree of resistance against buckling, particularly, if the can is drawn or extruded from relatively weak material, such as aluminum.

In accordance with this invention, a novel bottom wall having a specific profile has been devised which increases the pressure-buckling resistance of drawn, extruded and/or wall ironed cans by approximately 45 to 50 percent. In general terms, the profiled bottom wall of this invention comprises an annular chime formed in a bottom panel of a can which projects inwardly and upwardly from the body wall of the can at a predetermined angle, and an annular bead formed in the bottom panel of the can at the uppermost end of .the chime. This specified construction of the bottom wall substantially increases the pressure-buckling resistance of the cam bottom andpermits the can bottom to be made very thin without danger of buckling under the influence of internal pressure when beverages or pressurized materials are packaged in the can.

Accordingly, an object of this invention is to provide a can or can body whose particularly profiled bottom wall has improved pressure-buckling resistance as compared to conventional cans.

Another object of this invention is to provide a profiled bottom wall for extruded and wall ironed cans which permits the bottom wall of the can to be made very thin without danger of pressure-buckling when carbonated beverages or pressurized materials are packaged therein.

Other objects and advantages of the invention will be apparent to those skilled in the art from the following description of one specific embodiment thereof, as illustrated in the attached drawing, in which;

FIG. 1 is a fragmentary side elevational view with a portion removed for clarity of the bottom end portion of an extruded can body prior to being profiled in accordance with this invention;

FIG. 2 is a fragmentary side elevational view with a portion removed for clarity of the can bottom shown in FIG. 1, and illustrates the bottom wall profiled in accordance with this invention.

carbonated In FIG. 1 there is shown a bottom end portion (unnumbered) of an extruded and wall ironed can body 5 comprising a cylindrical body wall 10 and outwardly domed bottom panel 12 integrally joined to the body wall 10 at a peripheral juncture 14. The can body 5 is adapted to be profiled in accordance with this invention as will be more apparent hereafter, but the bottom panel 12 is initially outwardly domed on a radius R and is differentially thickened, as indicated by the different thicknesses T, and T When the bottom wall or panel 12 is profiled the excess material at the periphery thereof is redistributed by a stretching action to provide a uniform bottom thickness. The thickness T is approximately equal to the body wall thickness T The radius R, and thickness T, are chosen to provide adequate material for the profiled bottom wall or panel 12' shown in FIG. 2, which when formed from the material of the bottom panel 12, stretches the latter by approximately eighth inch.

In general, the profiled bottom wall 12' (FIG. 2) of this invention comprises an annular chime 16 formed adjacent to the peripheral juncture 14 which projects inwardly and upwardly therefrom at an angle A to the body wall 10. The lowermost end of the annular chime 16 is defined by a relatively sharp annular radius portion 17 having a sharp radius of curvature R at the point where chime I6 joins the body wall 10. The uppermost end of the chime 16 is defined by an annular bead portion 1-8 which has a relatively large radius of curvature R The length of the chime 16, as measured from the outside of the radii of curvature R and R is indicated by the dimension L. It will be appreciated by those skilled in the art that the particular value for the dimension L will be dependent on the value of the angle A and the relationship between the diameter D of the body wall 10 and the diameter D of the annular bead 18..More specifically, the dimension L will be approximately equal to (D D )/(2 Cos A).

The radius of curvature R and the diameter D of the annular head 18, taken in consideration with the angle A and the length L are the most important variables in the profiled bottom wall of this invention. The annular bead 18 by virtue of its annular shape and its semi-circular cross-section, is highly resistant to pressure-buckling, and it is positioned in such manner as to substantially increase the pressure-buckling resistance of the remaining portions of the bottom wall. For the purpose of analyzing the effect of the annular bead 18 upon the pressure-buckling resistance of the other portions of the bottom wall 12, vectors have been drawn on the right hand side of FIG. 2 indicating the direction of fluid pressure applied to the bottom wall 12' from within the can 5. It will be immediately apparent that the pressure applied directly to the annular head 18 will be ineffective to produce any buckling but will rather tend to compress the cross-section of the annular bead 18. The net downward force applied to the annular bead 18 is directly supported by the annular chime 16, which is placed in slight compression by the downward force. This, however, presents no problem with respect to buckling due to the relatively short length L of the annular chime.

The forces applied against the inner surface of the annular chime 16 have two effects. First they tend to bow the annular chime l6 outwardly, and second they tend to compress the annular bead 18 in the plane thereof in such manner as to tend to reduce the diameter D of the annular bead 18. However, due to the relative shortness of the length L, and to the inherent rigidity of the annular bead 18, strong resistance to these buckling forces is afforded even by the thinnest of bottom walls. Thus, it will be seen that the annular chime in combination with the annular bead provides a very substantial stiffening of the bottom wall 12' from its outer periphery to the inner periphery of the annular bead 18.

A central portion 20 of the bottom wall 12 is domed outwardly slightly along a relatively large radius R Pressure applied to the inner surface of the central portion 20 has two effects. First it tends to increase the outward bulge of the central portion 20, and second it tends to, in effect, roll the annular bead 18 down the annular chime 16. The first mentioned effect does not present any serious problem as long as there is some clearance between the bottom of the central portion 20, and the peripheral juncture 14 of the can, providing that the pressure is not great enough to rupture bottom portions 20. The second effect is counteracted by the inherent rigidity of the annular bead l8 and the support offered to it by the annular chime 16. It has been discovered by experimentation that the abovenoted stiffeningaction is very significant in the sense that it has been found to increase the resistance against buckling under the influence of internal pressure by approximately 45 percent in comparison with conventional profiled bottom walls.

Although the particular linear and angular relationships shown in FIG. 2 have been found to be preferable in the bottom walls of aluminum cans, these relationships may be varied within a reasonable degree without sacrificing too much of the increased pressure-buckling resistance. In some applications of the invention, an increase in pressure-buckling resistance of only 20 percent may be acceptable, and in these applications it may be desirable to alter the bottom profile relationships to satisfy other criteria, such as the ease of profiling the bottom wall. It will be apparent to those skilled in the art that the bottom wall shown in FIG. 2 will be easier to form if the radii R and R are increased, and although this would have the effect of lessening the resistance against buckling, it might be desirable in applications where the particular configuration shown in FIG. 2 provides an excessive amount of pressure-buckling resistance. In addition, with materials other than aluminum, it will be apparent to those skilled in the art that it may be desirable to make minor modifications in the relationships shown in FIG. 2 to suit the particular characteristics of the material employed.

In the particular example shown in FIG. 2, the can body is made of aluminum, and the relative dimensions of the bottom wall are as follow:

A=40, D =0.7 (D R 1.1 (D,), and R =2.0 1)- To form this particular bottom profile, the radius R in FIG. 1 is equal to 0.7 (D,) and the thickness T is equal to 1.5 (T These dimensions, however, may be varied within the following ranges without unduly reducing the increased resistance against buckling provided by the profiled bottom wall of this invention:

Dimension acceptable range of variation A 30 to 60 D, 0.6(D to 0.8 (D.) 0.7 (D,) to 1.5 (D,)

|.s T,) to 3.0 m)

departing from the spirit and scope of the invention asdefined in the appended claims.

We claim:

I. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall, an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly'projecting dome formed in said wall within the inner periphery of said annular bead, the angle between said annular chime and said body wall is greater than 30 and less than 60, and the radius of curvature of said annular bead in a plane containing the principal axis of the can body and extending radially of said body is less than three times the thickness of said bottom wall and greater than 1.5 times the thickness of said bottom wall.

2. The combination as defined in claim 1 wherein the diameter of said annular bead, measured across the annular center line thereof, is greater than 0.6 times the outside diameter of said body wall and less than 0.8 times the outside diameter of said body wall.

3. The combination as defined in claim 1 wherein the radius of curvature of said outwardly projecting dome is greater than 0.7 times the outside diameter of said body wall and less than 1.4 times the outside diameter of said body wall.

4.'The combination as defined in claim 1 wherein said can body is made of aluminum, the angle between said annular chime and said body wall being approximately 40, and the diameter of said annular bead as measured across the annular center line thereof is approximately equal to 0.7 times the outside diameter of said body wall.

5. The combination as defined in claim 4 wherein the radius of curvature of said annular bead in a plane containing the principal axis of the can body and extending radially of said body is approximately equal to two times the thickness of said bottom wall.

6. The combination as defined in claim 5 wherein the radius of curvature of said outwardly projecting dome is approximately equal to 1.1 times the outside diameter of said body wall.

7. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall,

an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly projecting dome formed in said bottom wall within the inner periphery of said annular head, said can body being made of aluminum, the angle between said annular chime and said body wall being approximately 40, the diameter of said annular bead as measured across the annular center line being approximately equal to 0.7 times the outside diameter of said body wall, and the radius of curvature of said annular bead is approximately equal to two times the thickness of said bottom wall.

8. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall,

an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly projecting dome formed in said bottom wall within the inner periphery of said annular bead, the angle between said annular chime and said body wall is greater than 30 and less than 60, said can body being made of aluminum, the diameter of said annular bead as measured across the annular center line thereof is approximately equal 0.7 times the outside diameter of said body wall, and the radius of curvature of said annular bead is approximately equal to two times the thickness of said bottom wall.

9. The combination as defined in claim 8 wherein the radius of curvature of said outwardly projecting dome is approximately equal to 1.1 times the outside diameter of said body wall. 

1. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall, an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly projecting dome formed in said wall within the inner periphery of said annular bead, the angle between said annular chime and said body wall is greater than 30* and less than 60*, and the radius of curvature of said annular bead in a plane containing the principal axis of the can body and extending radially of said body is less than three times the thickness of said bottom wall and greater than 1.5 times the thickness of said bottom wall.
 2. The combination as defined in claim 1 wherein the diameter of said annular bead, measured across the annular center line thereof, is greater than 0.6 times the outside diameter of said body wall and less than 0.8 times the outside diameter of said body wall.
 3. The combination as defined in claim 1 wherein the radius of curvature of said outwardly projecting dome is greater than 0.7 times the outside diameter of said body wall and less than 1.4 times the outside diameter of said body wall.
 4. The combination as defined in claim 1 wherein said can body is made of aluminum, the angle between said annular chime and said body wall being approximately 40*, and the diameter of said annular bead as measured across the annular center line thereof is approximately equal to 0.7 times the outside diameter of said body wall.
 5. The combination as defined in claim 4 wherein the radius of curvature of said annular bead in a plane containing the principal axis of the can body and extending radially of said body is approximately equal to two times the thickness of said bottom wall.
 6. The combination as defined in claim 5 wherein the radius of curvature of said outwardly projecting dome is approximately equal to 1.1 times the outside diameter of said body wall.
 7. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall, an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly projecting dome formed in said bottom wall within the inner periphery of said annular bead, said can body being made of aluminum, the angle between said annular chime and said body wall being approximately 40*, the diameter of said annular bead as measured across the annular center line being approximately equal to 0.7 times the outside diameter of said body wall, and the radius of curvature of said annular bead is approximately equal to two times the thickness of said bottom wall.
 8. In a can body having a body wall and a bottom wall integrally joined to said body wall at a peripheral juncture, the improvement comprising an annular chime formed in said bottom wall adjacent to said peripheral juncture and projecting inwardly and upwardly therefrom at a predetermined angle to said body wall, an annular bead formed in said bottom wall at the uppermost end of said chime, an outwardly projecting dome formed in said bottom wall within the inner periphery of sAid annular bead, the angle between said annular chime and said body wall is greater than 30* and less than 60*, said can body being made of aluminum, the diameter of said annular bead as measured across the annular center line thereof is approximately equal 0.7 times the outside diameter of said body wall, and the radius of curvature of said annular bead is approximately equal to two times the thickness of said bottom wall.
 9. The combination as defined in claim 8 wherein the radius of curvature of said outwardly projecting dome is approximately equal to 1.1 times the outside diameter of said body wall. 